Endless conveyor systems are typically used in long wall mining of coal and the like. An armored face conveyor (AFC) receives the mined material as it is stripped from the mine face, and moves it to a delivery station where it is transferred to a series of other endless conveyors until eventually reaching the aboveground location for further processing and use. Drive sprockets and idler drums are incorporated for driving and supporting the AFC tail drive unit and other conveyor apparatus. Because of the hostile operating environment and the bulky nature of the mined materials, such conveyor apparatus are constructed with very durable, heavy duty components, including heavy gauge conveyor chains and flight bars. Even under the best of conditions, the various working components required to move and support the AFC chain and flight bars, especially the support shafts and bearings, are subject to considerable wear. This is due, in part, to the weight of the chain and the tremendous forces needed to move the heavy aggregate loads.
Regular and frequent lubrication of the bearings in the drive sprocket and idler drum assemblies of the tail drive unit is essential, in order to minimize this wear. It further promotes smooth and efficient operation of the conveyor apparatus. It can be appreciated that maintaining an adequate lubricant supply around the bearings not only serves to preserve the bearings themselves, but also extends the service life of other components in the conveyor system and minimizes the power requirements. For example, well lubricated bearings of the tail drive unit enable the drive sprocket assembly to more freely rotate. This, in turn, reduces the load on the drive motor that rotates the sprocket. Accordingly, the service life of the drive motor is effectively extended, and the electric power needed to drive the motor is of course reduced.
During a typical AFC mining operation, coal or other in situ material is dislodged from the mine face and free falls a short distance to land on the conveyor pan. To ensure that most of the dislodged material lands on the conveyor, the conveyor is positioned as close to the mine face as possible. Positioning the AFC tail drive unit adjacent to the face of the mine makes it extremely difficult to access the drive sprocket and idler drum bearings on the face side (i.e. side next to mine face) of the conveyor. This inaccessibility dictates that an increased conveyor down time is required each time the apparatus is shut down to lubricate the bearings. The time loss is unusually extended because of the rigorous procedures that must be followed to prevent a mishap as the operator awkwardly climbs over the conveyor apparatus while holding and operating a lubrication gun. Moreover, the down time factor is multiplied by the number of drive sprockets and idler drum assemblies in the entire conveyor system. It is desirable, not only for the AFC tail drive unit, but the other endless conveyors to provide a placement next to the mine wall to conserve space.
One example of addressing this lubricating problem is found in U.S. Pat. No. 5,027,940 to Woodward. This reference discloses a lubricating system in a conveyor apparatus that accommodates the lubrication of rotary conveyor members from the opposing side of the conveyor. Lubricant is communicated through a line to the opposite side of the conveyor. The hydraulic line terminates at a stationary fitting, positioned on a fixed bearing tube at the end of the rotary shaft. Once the lubricant is introduced through this stationary fitting, it is communicated through an internal cavity in the support tube and ultimately reaches the bearings.
While the Woodward reference discloses an effective way to provide remote lubrication for conveyor apparatus bearings, it has several shortcomings. Perhaps the most significant shortcoming involves retrofitability. It is readily observed that the lubrication system of the Woodward reference is only suited for applications in conveyor apparatus having a fixed or stationary bearing mounting and lubricant fitting. Otherwise, the connection between the fitting and hydraulic line could not be established. The entire rotary support assembly of this conveyor apparatus cannot be removed and easily replaced (note in FIG. 3, the welded in place bearing tube 25). Thus, the lubrication system of the Woodward invention is adaptable for use in only a limited type of situation.
Another shortcoming of the Woodward reference is the additional time required during installation of a replacement rotary support assembly. Before servicing each rotary support member, the bearings, washers, seals and retainers must be separately removed, and then reinstalled at the work site (see FIG. 3). While this step, in itself, could be performed in a relatively short amount of time in a controlled repair area, it is difficult to do especially at a working mine face. The repetition of this step for each rotary support member and/or replacement bearings and the like, over the life of the conveyor can consume an appreciable amount of time.
Accordingly, there is clearly a need to provide a more convenient and efficient lubrication system for conveyor apparatus that accommodates remote lubrication; especially for the bearings of drive sprockets/idler drum assemblies of AFC tail drive units. Also, a lubrication system is sought that minimizes the removal/installation time of the replacement drive sprocket/idler drum assemblies, while also providing a simple and cost-effective design.